Pulsars, transients and relativistic astrophysics

Abstract:

We have measured the scattering time-scale, τ, and the scattering spectral index, α, for 84 single-component pulsars. Observations were carried out with the MeerKAT telescope as part of the Thousand-Pulsar-Array programme in the MeerTime project at frequencies between 0.895 and 1.670 GHz. Our results give a distribution of values for α (defined in terms of τ and frequency ν as τ ∝ ν^−α) for which, upon fitting a Gaussian, we obtain a mean and standard deviation of 〈α〉 = 4.0 ± 0.6. This is due to our identification of possible causes of inaccurate measurement of τ, which, if not filtered out of modelling results, tend to lead to underestimation of α. The pulsars in our sample have large dispersion measures and are therefore likely to be distant. We find that a model using an isotropic scatter broadening function is consistent with the data, likely due to the averaging effect of multiple scattering screens along the line of sight. Our sample of scattering parameters provides a strong data set upon which we can build to test more complex and time-dependent scattering phenomena, such as extreme scattering events.